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<h1>POI VIII Stage 3 Problem 5</h1>
<h1>Goldmine</h1>
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<P>Byteman, one of the most deserving employee of The Goldmine of Byteland, is
about to retire by the end of the year. The Goldmine management would like to
reward him in acknowledgment of his conscientious
work. As a reward Byteman
may receive a small lot - a rectangular piece of the mine's area with sides of
length <i>s</i> and <i>w </i>parallel to the axes of the coordinate system. He
may choose the location of the lot. Of course, a value of the lot depends on the
location. The value of the lot is a number of gold nuggets in the area of the
lot (if a nugget lies on the border of the lot, then it is in the area of the
lot). Your task is to write a program which computes the maximal possible value of
the lot (the value of the lot with the best location). In order to simplify we
assume that the terrain of the Goldmine is boundless, but the area of gold
nuggets occurrence is limited. 

      <H2>Task</H2>
<p>Write a program which:</p>
      <UL>
        <LI>reads from the text file KOP.IN the location of gold nuggets, </LI> 
        <LI>computes the maximal value of a lot (i.e. the maximal number of gold
          nuggets on the lot of given size), </LI> 
        <LI>writes the result in the text file KOP.OUT. </LI></UL>

<H2>Input</H2>
In the first line of the text file KOP.IN there are two positive integers <i>s</i> and <i>w</i> separated by a single space, (<I>1&lt;=s,w&lt;=10&nbsp;000</I>);
they denote the lengths of lot's sides - parallel to the OX-axe and OY-axe
respectively. There is one positive integer <i>n</i> written in the second line, (<I>1&lt;=n&lt;=15&nbsp;000</I>).
It denotes the number of nuggets in the area of the Goldmine. In the following <i>n</i>
lines there are written the coordinates of the nuggets. Each of these lines
consists of two integers <i>x</i> and <i>y</i>, (<i>-30&nbsp;000&lt;=x,y&lt;=30&nbsp;000</i>),
separated by a single space and denoting the <i>x</i> and the <i>y</i> coordinate
of a nugget respectively. 

<H2>Output</H2>
The text file KOP.OUT should contain exactly one integer
equal to the value of the most valuable lot of a given size.

<H2>Sample Input</H2>
<PRE>1 2
12
0 0
1 1
2 2
3 3
4 5
5 5
4 2
1 4
0 5
5 0
2 3
3 2
</PRE>

<h2>Sample Output</h2>
 <PRE>4</PRE>

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